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Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Pedro Falcato , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Kalesh Singh Modify smap_gather_stats() to use walk_page_range_vma() instead of walk_page_range() when walking page tables. walk_page_range() internally calls find_vma(), which asserts that mmap_lock is held. This assertion fails when reading /proc/pid/smaps under per-VMA locks (where mmap_lock is not held). walk_page_range_vma() walks a range within a single VMA and does not use find_vma(). It relies on the VMA lock instead (when configured with PGWALK_VMA_RDLOCK_VERIFY), making it compatible with per-VMA locks. Fixes: ea3085dd7a4e ("fs/proc/task_mmu: read proc/pid/{smaps|numa_maps} und= er per-vma lock") Cc: Andrew Morton Cc: Suren Baghdasaryan Cc: Liam R. Howlett Cc: Lorenzo Stoakes Signed-off-by: Kalesh Singh --- fs/proc/task_mmu.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index d32408f7cd5e..5d301bdd05fc 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1369,9 +1369,12 @@ static void smap_gather_stats(struct proc_maps_priva= te *priv, struct mem_size_stats *mss, unsigned long start) { const struct mm_walk_ops *ops =3D get_smaps_walk_ops(priv); + unsigned long end =3D vma->vm_end; + + start =3D start ?: vma->vm_start; =20 /* Invalid start */ - if (start >=3D vma->vm_end) + if (start >=3D end) return; =20 if (vma =3D=3D get_gate_vma(priv->lock_ctx.mm)) @@ -1401,10 +1404,7 @@ static void smap_gather_stats(struct proc_maps_priva= te *priv, } } =20 - if (!start) - walk_page_vma(vma, ops, mss); - else - walk_page_range(vma->vm_mm, start, vma->vm_end, ops, mss); + walk_page_range_vma(vma, start, end, ops, mss); =20 reacquire_rcu(priv); } base-commit: b95f03f04d475aa6719d15a636ddf32222d55657 --=20 2.55.0.229.g6434b31f56-goog